At least 58 people have died in the air-toxic gas attack in Syria's north-west.

The Syrian Observatory for Human Rights said on Tuesday that the attack was carried out in the town of Seikhun in Idlib province.The company said that 35 people of the city were killed due to poisonous gas. More than half of people suffer from respiratory and other problems. However, the London-based company could not give the name of the incident in what happened to the gas.The agency also said that it is not certain that the Syrian air force or not the government ally of the Russian Air Force launched this attack. The casualties are all civilians. Among them, there are 9 children.